Method for heavying polycyclic substances

ABSTRACT

METHOD FOR HEAVYING POLYCYCLIC SUBSTANCE, WHEREIN THE CRUDE MATERIAL IS TREATED WITH AN OXIDIZING AGENT, AND THEN TREATED WITH AMMONIA OR AMINES.

Feb. 27, 1973 TADASHI ARAKI ET AL METHOD FOR HEAVYING POLYCYCLICSUBSTANCES Filed Dec. 28, 1970 Tadashi ARAKI KiIO ASANO Hitoshi TAKITATakao AWAO BY W M a hx,

3,718,574 METHOD FOR HEAVYING POLYCYCLIC SUBSTANCES Tadashi Araki, KiroAsano, Hitoshi Takita, and Takao Awao, Tokyo-to, Japan, assignors toKureha Kagaku Kogyo Kabushiki Kaisha, Chuo-ku, Tokyo-to, Japan FiledDec. 28, 1970, Ser. No. 101,510 Claims priority, application Japan, Dec.29, 1969, 45/105,232 Int. Cl. Cc 3/02 US. Cl. 208-44 5 Claims ABSTRACTOF THE DISCLOSURE Method for heavying polycyclic substance, wherein thecrude material is treated with an oxidizing agent, and then treated withammonia or amines.

BACKGROUND OF THE INVENTION This invention relates to a method ofheavying organic compounds containing polycyclic condensation structureas the principal constituent.

Heretofore, there have been known many expedients for heavying tars andpitches of coal or petroleum type, e.g., extraction, distillation,heat-treatment, oxidation-treatment with gas such as air, oroxidation-treatment with liquid such as nitric acid, aqueous solution ofhypochlorous acid, etc.

Of these, extraction and distillation are to retain highmolecular-weightcomponents by simply removing components of relatively low molecularweight from those Constituting the tars and pitches, the treatments ofwhich cannot be called heavying of the substance in the true sense ofthe word. Furthermore, with such methods, the rate of yield of theresultant heavy substance with respect to the starting material wouldinevitably be extremely small.

The method of heavying tars and pitches by means of the heat-treatmentis based mainly on polycondensation of the substances due to cutting ofthe side chains in the molecules, hence it is difiicult to proceedsmoothly unless the treatment temperature is relatively high, e.g.,above 400 C. For this reason, addition of Friedel-Krafts type catalysthas been resorted to very often as an eifective expedient.

Heavying of tars and pitches by oxidation-treatment is considered totake place by that oxygen is introduced into molecules of the crudematerial as it is or in the form of a functional group containingoxygen, where it is combined with hydrogen and carbon atoms to formwater (H O), carbon dioxide (CO and/or carbon monoxide (CO) anddissociate from the material, at which time matrices of difierentmolecules in the substance are combined together to become heavy. Incase oxygen constitutes molecules such as CO CO, etc., there often takesplace a phenomenon such that it combines with carbon atoms in thematrix. In other words, carbon atoms in the matrix are pulled out withthe consequent destruction of the matrix constitution. This wouldinevitably bring about various unfavorable eifects on the material andproduct produced thereby such that not only weight of the substancereduces besides dissipation of the low-molecular-weight components, butalso the inherent characteristics of the crude material is impaired bythe destruction of the matrix structure, and that crystallinity ofcarbon molecule in the carbon articles obtained from this heavysubstance as the material is impaired.

SUMMARY OF INVENTION It is therefore the primary object of the presentinvention to provide an improved method of heavying tars,

' United States Patent Ofice 3,718,574 Patented Feb. 27, 1973 pitchesand other resinous substances without spoiling the matrix structurewhich is the principal constituent of the crude material.

It is another object of the present invention to provide a method ofheavying those hydrocarbon compounds with a polycyclic condensationstructure as the principal constituent, wherein the substance issubjected to an oxidizing treatment with an oxidizing agent in gaseousor liquid form, thereafter it is further treated with ammonia or amines.

The foregoing objects and other objects as well as the principle andoperation of the present invention will become more apparent from thefollowing detailed description and a few preferred examples of thepresent invention when read in conjunction with the accompanyingdrawing.

BRIEF EXPLANATION OF THE DRAWING FIG. 1 is an X-ray microphotograph of acarbon article obtained from the material treated by the methodaccording to the present invention; and

FIG. 2 is another X-ray microphotograph of a carbon article obtainedfrom the material treated by the conventional method.

DETAILED DESCRIPTION OF THE INVENTION The invention will now bedescribed hereinbelow, in sequence, with respect to the class of crudematerials to be treated, actual treatment steps, effects to be resultedfrom the present invention is comparison with the known arts.

The term heavying used in the present invention is meant by thatmolecules of the components in the substance to be treated causepolymerization or condensation to increase molecular weight thereof,whereby various phenomena such as infusibilization, increase in boilingpoint, increase in melting point, and so forth appear in the resultantsubstance.

The crude materials, to which the present invention is directed arethose hydrocarbon compounds containing as the principal componentthereof a polycyclic condensation structure (preferably havingaromaticity having more than two rings with or without alkyl radicalattached thereto. These compounds may be used individually or in theform of a mixture of some of them. They may also be used in any formsuch as powder, liquid, or even in shaped article like fiber, film, rod,etc.

Examples of these hydrocarbon compounds are: aromatic or aliphatichydrocarbons and their alkyl-derivatives such as naphthalene, tetraline,decaline, indene, acenaphthene, pyrene, crisene, naphthacene, perylene,triphenylene, etc.; distilled component of petroleum of 200 C. andabove; by-products in the petroleum refining industries such as heavyoil, and pitches (e.g., visbreaker residual oil, cyclic oil fromcontact-cracking, asphalt, coker distillate oil, de-alkylated residualoil, etc.); oily or solid substance produced at the time of petroleumcracking in the petro-chemical industries where ethylene, acetylene,propylene, etc. are produced; and oily and pitchy substances obtained inthe coal distillation industries. These substances generally possess theH/C atomic ratio of 0.4 to 1.2.

The first 'step of subjecting these substances to the oxidizingtreatment as mentioned above is arbitrarily selected from theconventional oxidizing reactions. Examples of these known oxidizingtreatments are: 1) treatment with one kind of gas or a mixture of morethan two kinds of gases such as ozone, oxygen, air, halogens, S0 oxidesof nitrogen, and so forth; and (2) treatment with solution of nitricacid, sulfuric acid, nitrous acid, dichromate, permanganate, or thelike. Any other oxidizing treatment may also be put into practiceeffectively.

The treatment temperature is generally in the range of from C. to 400 C.More generally, there may be adapted such a condition that no remarkableconsumption of the substance to be treated nor destruction of the matrixmolecules due to the oxidation takes place, and yet sufficient effect ofoxidation may be exhibited.

It has been verified by physical method such as infrared ray spectrum aswell as by chemical assays that, by the abovementioned oxidizingtreatment, at least one kind of a substituent radicals such as C=O(quinone, ketone, aldehyde, carboxylic and like other types), -OH(phenol, alcohol, carbonic acid, and like other types), -NO =NOH, -CH X(X is a halogen), CX

etc. is introduced into the crude material.

Upon completion of the oxidizing treatment, the crude material may be,depending on necessity, molded into a shaped body for the subsequenttreatment with ammonia or amines.

The second step of treatment with ammonia or amines will now beexplained hereinbelow.

Ammonia may be advantageously used in gaseous form such as, for example,pure ammonia gas or a mixture of ammonia and air or an inactive gas suchas nitrogen. It is worthy of note to mention that use of ammonia in theform of mixture with air is to carry out concurrently the oxidationtreatment due to oxygen contained in air and the ammonia treatment. Samecan be said of a mixture of ammonia and air containing ozone. It hasbeen verified by the present inventors that, in the case of using amixture of ammonia and air, there first takes place introduction intothe crude material of the abovementioned functional group by the actionof the oxidizing agent, and then the reaction due to ammonia. From thisfinding, it should be correctly understood that, while the reactiontakes place in one step, at a glance, it actually involves two-stepreaction. Such case also falls under the category of the presentinvention except for a case, wherein an oxidizing agent and ammonia oramines mutually react to produce an entirely different compound, e.g.,N0 gas and ammonia which react to produce ammonium nitrite, and nitricacid and ammonia to form an ammonium salt to exhibit no effect at all.

Amines to be used are: primary amines such as methyl amine, ethyl amine,butyl amine, aniline, etc.; secondary amines such as dimethyl amine,diethyl amine, dibutyl amine, diphenyl amine, etc.; polyamines such aspiperidine, ethylenediamine, diethylene triamine, triethylene tetramine,benzidine, p-p'-diamino-diphenyl ether, etc.; and a substance like thecrude material to be used in the present invention, into which more thanone number of amino group is introduced. These amines may also be usedin the form of gas, liquid, or a mixture powder thereof.

The temperature for the treatment with ammonia or amines, in general,ranges from a room temperature to 400 C. or so. The treatment time isgoverned by the treatment temperature.

The crude material which has been made heavy by the aforedescribedtwo-step treatment possesses various effects as mentioned hereinbelow.

(1) High carbon yield: According to the present method, substantiallyall of carbon atoms in the substance to be treated remain in the productwhich has been made heavy, i.e., the least carbon atom escapestherefrom. The reason for this is yet to be clarified, but the followingassumption is possible. Most of the functional groups containing oxygenor halogen and introduced into the crude material at the first step ofthe treatment are substituted for a functional group containing nitrogenatom due to isolation of water or halogenated hydrogen from thesubstance at the second stage of the reaction, or is combined with othermatrix molecule by the help of the nitrogencontaining functional group.When the crude material is further heated, the nitrogen-containingfunctional group pulls off hydrogen within the molecule or from themolecular chains to isolate hydrogen in the form of H 0, N or NH and, atthe same time, causes the matrix molecules to directly combine eachother.

In the abovementioned reaction mechanism, those which dissociate arealways compounds of hydrogen and other atoms contained in the functionalgroups which have already been introduced into the crude substance atboth first and second reactions such as, for example, H O, HX, N NHetc., whereby heavying of the crude substance and dehydrogenation can becarried out effectively. In this case, as the carbon atom dissociatesfrom the substance to an extremely small degree, the rate of carbonyield (content of carbon atom in percent by weight remaining in theproduct rendered heavy) becomes remarkably high. Thus, the leastdissociation of carbon atoms from the substance endorses that nodestruction of the matrix structure accrues from the treatment, and, inaddition, it is really surprising to note that tars and pitches of thecoal and petroleum types have been possibly rendered heavy orinfusibilized with high rate of carbon yield, the industrialsignificance of which is great.

(2) No catalyst required: It has been the practice to often use metallicsalts such as AlCl FeCl and so forth as the Friedel-Krafts type catalystto render a substance heavy. However, as residue of these catalystsexisting in the heavy substance has been in most cases a cause forchange in quality of the heavy substance to be stored as time goes on,or brings about deleterious effect at the time of use thereof, it isnecessary to remove such residue beforehand, the removing work of whichis complicated and costly. The present invention needs not use suchcatalyst at all in the course of treating the crude material to berendered heavy, in which respect great advantage of the inventionresides, too.

(3) Easiness in regulating the reaction conditions: According to thepresent invention, in still other aspect of its advantage, it ispossible to arbitrarily regulate the first and second reactions byproper selection of the reaction conditions. This means that not onlythe degree of heavying of the substance can be controlled, but alsodifficulty or easiness of orientation of the component molecules can becontrolled.

In general, mechanical as well as physical properties of carbon andgraphite materials depends largely on the degree of crystallization inthe materials. Organic substances are generally carbonized byheat-treatment in a non-oxidizing atmosphere of 500l000 C. 'In thiscase, aromatization of the substance takes place prior to thecarbonization thereby to form a network plane of the polycycliccondensation structure. When a plurality of the network planes arelaminated to constitute microcrystallite, it is called a carbonmolecule. Random arrangement of such micro-crystallites is namedamorphous carbon. Further heat-treatment of this organic substance to atemperature in the vicinity of 3,000 C. causes growth of thecrystallites and simultaneously increases the degree of the crystalorientation. The degree of the crystal growth at this time differsnaturally from one crude material to another, and also varies to a greatextent depending on the treatment conditions. That is, in order for thenetwork planes consisting of polycyclic aromatic condensation structureto be laminated, the crude substance should preferably be rich inaromatic components. In the course of the carbonization, when the crudesubstance undergoes very complicated heavying processes which preventthe network planes from growing and laminating (i.e., three-dimensionalpolymerization), crystallinity of the substance is hindered to result incarbon material having difficult degree of graphitizability which isgenerally called a hard carbon material. On the contrary, a carbonmaterial having easy degree of graphitizability is called a soft carbonmaterial.

According to the findings heretofore made based on various experiments,a most general expedient of producing the hard carbon material is tosubject the crude substance to the oxidizing treatment at a relativelylow temperature of less than 300 C. By this low temperature oxidation,there are formed very complex threedimensional bridging connectionsamong the carbon molecules with the consequence that crystal growth ofthe carbon molecules in the course of the carbonization process isremarkably hindered. If there exists a functional group containingoxygen, the oxygen not only forms water at the time of thermaldecomposition, causing dehydrogenation, but also combines with carbon toform carbon dioxide, and carbon monoxide, and dissociates from thesubstance. At this time, the rate of carbon yield is reduced andsimultaneously the ring structure of the matrix molecules is destroyed,which also become the cause for deterioration in crystallinity of carbonmolecules.

In the present invention, the crude material to be treated does notnecessarily become the hard carbon material, even when a functionalgroup containing oxygen is introduced thereinto by the first stepreaction, but it is rather turned into the soft carbon material of easygraphitizability in some cases. The reason for this may be that, sincemost part of the functional group introduced into the crude material atthe first step reaction is replaced with a functional group containingnitrogen at the second step reaction, there takes place no hindranceagainst the crystal growth. Although it might be a real wonder why thenitrogen-containing functional group does not hinder the crystal growth,this regulability of the crystal growth may be said to be one of theunique features of the present invention.

As has been made apparent from the foregoing description, the presentinvention is too provide a motel method of heavying organic compoundscontaining polycyclic aromatic condensation structure as its principalconstituent, in which various crude materials in either form ofsolution, liquid, solid, etc. may be effectively rendered into heavysubstance as desired. The method itself may'find its application in thefield of manufacturing a binding material for carbonaceous or ceramicsarticles, and is also effectively applicable in producing carbonaceousarticles themselves. For example, fibers or films made of aromatic pitchmaterial obtained from heatcracking of petroleum or thermaldecomposition of coal tar may be easily rendered heavy and infusible bythe present method with the result that they can be processed intocarbon fibers and films with remarkably high carbonization yield andwithout causing deformation in the articles due to the high temperaturecarbonization treatment. Furthermore, unlike the case of heavying thematerial by the conventional oxidation treatment alone, as there takesplace no hindrance against the crystal growth, an extremely easygraphitizable article may be obtained by making good use of thestructural characteristic of the crude material. Since the carbon fibersand the like are strongly required from all concerned to have highdegree of graphitizability, elasticity as well as mechanical strength,the effect obtained from the present invention is consideredoutstanding.

It is further possible to obtain carbonized or graphitized articleswithout losing its original shapes thereof from a pitch powder which ismolded into a required shape and rendered heavy in accordance with thepresent invention. As the method of shaping in this case, both powderforming method and slurry casting method may be utilized.

Even in the case of using cokes, graphiti'c aggregate, or refractoryaggregate together with the crude material to be treated in accordancewith the present invention as a binder, the present method exhibitsexcellent infusibilization effect, whereby shaped carbon articles'of theleast porosity and high tenacity may be produced with a high rate ofcarbonization. As the impregnation treatment after roasting becomesdispensable in this case, economy in manufacture is greatly improved.

It may be emphatically repeated that, in the above- .lescribed shapingmethod in common, the crude material may first be oxidation-treated,after which it is shaped into an article, and then the shaped article issubjected to the second treatment with ammonia or amines.

The present invention is also advantageously used in the case ofmanufacturing electrodes, commutators, and sliding material whichrequire high degree of graphitizability, or carbon articles for acertain kind of machinery requiring high mechanical strength.

Thus the present invention has brought into the field of carbon andceramic industries a new method of heavying the crude substances, bywhich production of carbon and ceramic articles of highly improvedproperties has been made possible.

PREFERRED EMBODIMENTS In order to enable persons skilled in the art toreduce the invention into practice, the following examples arepresented. It should, however, be noted that these examples areillustrative only and they do not intend to limit the scope of thepresent invention.

EXAMPLE 1 Crude oil of Seria origin was preheated to 500 C., and thenatomized into steam heated to 2,000 C. to mix therewith. The crude oilwas pyrolized (reaction temperature of approximately 1,200 C.) to resultin a tarry substance at a rate of recovery of about 30%. This tarrysubstance was distilled under a reduced pressure of 5 mm. Hg to divideit into a distillate component (hereinafter referred to as A) of 300 C.or below and a residue (hereinafter referred to as B) of nearly sameamount as the former.

As the results of various measurements on the A substance by way ofnuclear magnetic resonance (N.M.R.) spectrum, infrared ray spectrum,elementary analysis, gas chromatography, molecular weight, etc., it wasfound that this substance was a liquid composed of a mixture of variouskinds of molecules representable by a model, in which a small number ofshort chain alkyl radicals are coupled with a polycyclic aromaticcondensation structure having 2 to 4 aromatic rings as the mainskeleton.

This substance was first contacted with air containing 40% by weight ofN0 at a temperature of 120 C. for a time period of 60 minutes and 120minutes, respectively, and then contacted with ammonia gas at 250 C. for30 minutes, whereupon pitch having a softening point of 70 C. and 380C., respectively was obtained at a rate of recovery of 90% with respectto the A substance. The pitch having the softening point of 70 C. isdesignated as pitch C, and that having the softening point of 380 C. isdesignated as pitch D.

The major properties of the above pitches C and D as measured are shownin the following Table 1, from which it is recognized that the substancewas effectively made heavy.

Carbon content (wt. percent) Hydrogen content (wt. percent) Oxygencontent (wt. percent) Nitrogen content (wt. percent). 1. 40 2 20 Rate ofcarbonizatlon 3 (wt. per nt) 5 74 88 Carbonization yield (percent) 5 90H/C atomic ratio 0.98 0. 55 0. 48

l Approximate.

2 Measurement impossible due to existence of insoluble components.

3 Rate of Carbonization herein used is the quantity in percent by weightof the residual carbonized material, when a specimen is placed in acrucible and heated to a temperature of 1.000 C. at a temperature userate of 5C. per minute in nitrogen atmosphere.

The pitch C thus obtained was added to doromite clinker or magnesiaclinker at a rate of 6% by weight, and kneaded for 30 minutes at 100 C.,after which the kneaded material was shaped into a mold under pressureof 500 kg./cm. to obtain a short column having dimensions 50 x 50 x 80mm. The compression strength of this column measured at a normaltemperature indicated 79 kg./cm. In contrast to this, the compressionstrength of a column of the same dimension obtained from coal tar pitchhaving the softening point of approximately 80 C. in the same manner asmentioned above was no higher than 60 kg./cm. This fact signifies thatshaped articles of the heavy pitch according to the present inventionhas higher compression strength in their raw state than that of theordinary pitch, so that they provide good workability in variousmanufacturing processes, hence remarkable contribution to productivity.

From the pitch D, slurry was prepared by mixing and kneading 25 g. ofthe pitch material, 20 g. of ethyl alcohol, and 100 g. of water in aceramic ball mill for laboratory experiment of a 1-liter capacity for 8hours at a room temperature. The slurry was shaped into a small cruciblehaving wall thickness of about 3 mm. by pouring it in a plaster mold ina molding time of 5 seconds. The shaped article was first dried at aroom temperature, thereafter it was further dried at a temperature of100 C. Upon completion of the drying, the shaped article was subjectedto carbonization treatment in a nitrogen atmosphere by elevating atemperature to 1,400" C. at a temperature rise rate of 2 C. per minuteup to 220 C., and 5 per minute thereafter. The reduction in diameter ofthe crucible in the course of the carbonization treatment wasapproximately The resulted carbonized crucible possessed porosity of8.5% and bulk density of 1.57.

EXAMPLE 2 The residual substance B resulted from the distillation underreduced presure as explained in Example 1 above was found to be a pitchhaving a melting point of about 200 C. and composed of a mixture ofvarious compounds with a polycyclic aromatic condensation structurehaving more than 4 aromatic ring in average as the matrix, as theresults of various measurements by way of nuclear magnetic resonance(N.M.R.) spectrum, infrared ray spectrum, elementary analysis, gaschromatography, molecular weight, etc. The major properties of the pitchB as measured are as follows.

TABLE 2 Properties: Pitch B Mean molecular weight, approx 600 Carboncontent (wt. percent) 95.88 Hydrogen content (wt. percent) 4.01 Sulphurcontent (wt. percent) 0.08 H/C atomic ratio 0.5

This pitch B was carbonized in nitrogen gas by being heated to 1,000 C.,thereafter it was further heated to 2,400 C. in argon gas to begraphitized. On conducting an ordinary X-ray measurement, the productwas recognized to be a soft carbon material of excellentgraphitizaability having the value of the graphite crystal spacing Co of6.765 angstroms as determined from the crystallographic plane index dThe pitch material was spun into pitch fibers of 10 microns in averagediameter by means of a centrifugal spinning machine having a rotarycylinder of 150 mm. in diameter and 30 mm. in depth and provided with120 nozzles of 0.7 mm. in diameter each, and under the spinning rate of2,000 m./min. and the stretch ratio of 5,000 at a temperature of 300 to330 C.

The fibers were divided into two bundles, one of which was heat-treatedin air containing 30% by volume of ammonia gas starting from a roomtemperature up to 300 C. at a temperature rise rate of 1 C. per minuteso as to be made heavy and infusible (hereinafter referred to as No. 1batch), and the other of which was also heat-treated in air alonestarting from a room temperature up to 300 C. at a temperature rise rateof 1 C. per minute so as to be made heavy and infusible (hereinafterreferred to as No. 2 batch). Subsequently, both batches were heated in anitrogen gas atmosphere up to 650 C. at a rate of 5 C./min., at whichtemperature a stress of 0.4 t./cm. was imparted by using a weight to thebatches, while continuing heat-treatment up to a temperature of 850 C.,thereafter the fibers were further heat-treated up to 1,600 C. at a rateof 20 C./min. without imparting load. Further graphitization treatmentwas conducted in argon gas by elevating temperature up to 2,400 C. at arise rate of 20 C./min., while imparting stress of 1.2 ton/cm. to thefibers.

The graphite fibers thus obtained possessed tensile strength of 17tons/cm. in No. 1 batch and 14 tons/ cm. in No. 2 batch, and Youngsmodulus of 3,300 tons/cm. and 2,800 tons/cmfi respectively. Through anX-ray observation, it was verified that the network plane orientedwithin the range of :10 degrees from the axial direction of the fiberswas 91% in the case of No. 1 batch and in the case of No. 2 batch, theformer being superior to the latter.

EXAMPLE 3 A pitchy substance obtained from heat-treatment oftetrabenzo-(a,c,h,j)-phenazine in a nitrogen atmosphere at 580 C. for 60minutes was determined as a result of analyses to be a mixture ofaromatic substances having large polycyclic condensation structure whichis presumed to have been formed by condensation of tetrabenzo-(a,c,h,j)-phenazine due to dehydrogenation of 2 to 4 hydrogen atoms. Thepitchy substance had its softening point of about 300 C.

This pitch was melt-spung into pitch fibers of 10 to 12 microns indiameter by extrusion method utilizing a spinning machine having fivenozzles of 0.5 mm. in diameter each and at a spinning rate of to 150m./min. at a temperature range of from 370 to 380 C.

The thus obtained pitch fibers were heat-treated in air containing 20%by volume of N0 gas at 200 C. for 30 min. Upon completion of theheat-treatment, the fibers were divided into two bundles, one of whichwas subjected to further heat-treatment in methylamine gas at 200 C. for30 minutes. By this subsequent treatment, the fibers were recognized tohave been made heavy to such an extent that no softening phenomenontakes place at all.

When the treated fibers were carbonized in a nitrogen gas atmosphere byraising temperature up to 1,000 C. at a rise rate of 5 C./min., carbonfibers of excellent orientation was obtained as shown in the X-raymicrograph of FIG. 1. The degree of orientation was recognized to be 83%from analytical strength, and the fact that the carbon fiber of suchfavorable orientation was obtained by the heat-treatment at 1,000 C. isthe characteristic point of the present invention.

The other bundle of the divided pitch fibers was further heat-treated inair containing 20% by volume of N0 at 200 C. for 60 minutes, but notreatment with methylamine, and then carbonized in a nitrogen gasatmosphere by raising temperature up to 1,000 C. at a rise rate of 5 C./min. The resulted carbon fibers were of amorphous structure as seen fromFIG. 2.

EXAMPLE 4 From various analyses, it was verified that coal tar pitchhaving softening point of about 80 C. possessed a mean molecular weightof 400 and below, and was composed of a mixture of various compoundshaving some numbers of aliphatic side chains with a polycyclic aromaticcondensation structure having more than 3 aromatic rings as theprincipal constituent.

When 300 g. of this coal tar pitch was kneaded in a laboratory kneaderof a small size at a temperature of from 100 to C. for 30 minutes, whileblowing air containing 30% by volume of N0 gas therein-to, and then theresultant product was observed through infrared ray spectrum, it wasfound that radicals such as C=O, --N'O etc. were introduced into thepitch.

The thus oxidized pitch was divided into two batches, one of which washeat-treated for 5 minutes in ammonia gas at 200 C., when the softeningpoint thereof became approximately 400 C., and the other of which wastreated for air-oxidation at 200 C. for 30 minutes, the softening pointthereof having been about 360 C.

These heavy pitches were pulverized in a ball mill for five hours toobtain fine pitch powder of 200 meshes and below. The pitch powder wasthen molded into discs of mm. thick and 30 mm. in diameter bycompression molding under pressure of 400 kg./cm.

The discs were heated to a temperature of 2,800 C. at a rise rate of 1C./min. in a nitrogen atmosphere. The discs treated with ammonia gas atthe stage of the raw material was found to have 9.5% of porosity, 98 ofShore hardness (Hs), 630 kg./cm. of bending strength, 3.37 angstroms ofthe network plane interval determined by the X-ray diffraction, andgraphitizability of medium degree. Whereas, the discs treated forair-oxidation, but no ammonia gas treatment, was found to have 3.39angstroms of the netwonk plane interval determined by the X-raydiffraction, and lgraphitizability of diflicult degree. The mechanicalproperties of these discs could not be measured accurately due to thedeformation caused to some extent by generation of air voids within thediscs in the course of the temperature elevation.

What we claim is:

1. A method for the production of pitch having an increased carbonyield, which comprises the steps of first reacting a raw material whichis a pitch composed primarily of a condensed polycyclic aromaticcompound, or a mixture of such compounds, having more than two rings 10with or without an alkyl side chain attached thereto with an oxidizingagent at a temperature of from 0 C. to 400 C., and subsequently treatingthe oxidized material with a substance selected from the groupconsisting of ammonia, amines, and a mixture of ammonia and nitrogen ata temperature of from room temperature to 400 C.

2. The method as defined in claim 1, in which the raw material isreacted with a mixture of ammonia gas and an oxidizing agent selectedfrom the group consisting of air, oxygen, and ozone.

3. The method as defined in claim 1, in which the amine to be used inthe second treatment is selected from the group consisting of methylamine, ethyl amine, butyl amine, aniline, dimethylamine, diethyl amine,dibutyl amine, diphenyl amine, piperydine, ethylene diamine, diethylenetriamine, triethylene tetramine, benzidine, p-pdiamino-diphenyl ether,and a substance composed of polycyclic condensation structure havingmore than two rings with or without alkyl side chains attached thereto,in which at least one amine group is introduced.

4. The method according to claim 1, in which the raw material to betreated is in liquid state.

5. The method according to claim 1, in which the raw material to betreated is in solid state.

References Cited UNITED STATES PATENTS 2,026,039 12/ 1935 Hoover 208-443,493,409 2/ 1970 Koons 208-44 1,868,879 7/ 1932 Broadhead 208-442,980,601 4/ 1961 Meigs 208-44 DELBERT E. GANTZ, Primary Examiner V.OKEEKFE, Assistant Examiner

